Re: [Xenomai] XDDP and inter-driver API.

[Philippe Gerum <rpm@xenomai.org>]

On 07/10/2012 01:23 PM, Sunetra Sashi wrote:
>
> What is the recommended methodology for kernel space modules to
> communicate with each other across the Linux-Xenomai space?

There is no recommended methodology for this: kernel space should run 
within the linux domain only, or within the Xenomai domain only via the 
inter-driver RTDM interface, or should communicate with user-space only 
via a driver interface. rt <-> nrt within kernel space can be done using 
a low level mechanism, but there is no high level IPC for this.

Again, if your kernel space code is actually an application, spare 
yourself a lot of pain, and move it to userland.

>
> I corrected the rtipc rtdm device as a protocol device (I must have
> changed it in error) and I am able to load the xeno_rtipc.ko now.
> However, the socket open still fails with the same error code.
>
> Thanks
>
>
>                  I am making these calls from within the kernel, not
>         from user space.
>                  Hence I ended up using rtdm calls instead
>
>
>
>              /dev/rtp0 is a non-real-time user-space endpoint for the
>              communication, between a regular linux application and a
>         real-time
>              component. It does not make sense to open it from kernel space.
>
>
>         My intent here is to set up something similar to xddp-echo.c
>           (RT - Non
>         RT communication) but in kernel space instead. How should I go about
>         creating the Linux endpoint for XDDP in the kernel?
>
>
>     There is no direct way for that, this device/protocol is not
>     intended for this purpose. This is a regular linux application to
>     Xenomai real-time communication path, nothing else. Regular linux
>     applications live in userland, only.
>
>     We don't recommend building applications in kernel space.
>
>
>
>
>
>
>
>                           Do I need to install any specific xenomai
>         modules for
>                  this to work?
>
>
>                       Obviously, yes. Check IPC drivers in the "Drivers"
>         sub-menu
>                  of the
>                       Xenomai configuration. You need to have
>                       CONFIG_XENO_DRIVERS_RTIPC_XDDP enabled.
>
>
>                  I already checked this in the configuration, It is enabled.
>                  Should this
>                  also be set to y? CONFIG_XENO_DRIVERS_RTIPC. In my
>         configuration
>                  it is
>                  set to m.
>
>
>              Did you load the xeno_rtipc module then?
>
>
>         It is not loaded. But I got an error when I did that.
>         Xenomai: assertion failed at /.../kernel/xenomai/skins/)
>         Xenomai: RTDM: missing open handler
>
>
>     It does not make any sense. This assertion can only trigger for a
>     named device, not a protocol device. RTIPC is a protocol device.
>
>     - did you change any of the driver code?
>     - what command did you use to load the module, verbatim?
>
>         insmod: error inserting 'xeno_rtipc.ko': -1 Invalid parameters
>
>
>
>                  Should I see any modules loaded in
>                  /proc/xenomai/rtdm/protocol_____devices?
>
>
>              Yes.
>
>
>
>
>                           Thanks
>                           Shweta
>
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>
>                       --
>                       Philippe.
>
>
>
>
>
>              --
>              Philippe.
>
>
>
>
>
>     --
>     Philippe.
>
>
>


-- 
Philippe.